Conversion of hydrocarbon oils



Feb. 8, 1938. 4 K SWARTWOOD 2,107,454

CONVERSION OF HYDROCARBON OILS Filed. Oct. 26, 1933 FRACTIONATOR FURNACE 67 INVENTOR KENNETH i: TWOOD Patented Feb. 8, 1938 UNITED STATES PATENT OFFICE CONVERSION OF HYDROCARBON OILS Application October 26, 1933, Serial No. 695,267

2 Claims.

This invention refers particularly to an improved process and apparatus for the conversion of hydrocarbon oils of relatively wide boiling rangesuch as, for example, crude petroleum containing appreciable quantities of good antiknock gasoline or gasoline fractions, intermediate fractions and high-boiling fractions.

In the process of the present invention topping, pyrolytic conversion and flash distillation are combined in a novel and advantageous. manner so as to recover maximum yields of good antiknock motor fuel and a good quality fuel oil residue from the crude oil charging stock with minimum yields of coke and gas. Any lowis boiling, components of the crude, meeting standard requirements for good quality motor fuel, particularly with respect to their antiknock value, are recovered without appreciable conversion, together with low-boiling motor fuel products of the first conversion stage of the process. Intermediate fractions of the charging stock, including any gasoline fractions of inferior antiknock quality as well as, when desired, somewhat higher boiling materials such as kerosene or kerosene distillate, light gas oil and the like are subjected to pyrolytic conversion in the first conversion stage of the process, for the recovery of additional yields of good quality motor fuel fractions, and the highly heated products from the heating coil of the first cracking stage are quenched or cooled sufficiently to prevent an excessive further conversion by commingling therewith the crude oil charging stock for the process, thereby supplying heat to the crude for the topping and fractionating operation. Bottoms from the topping operation and high-boiling conversion products from the first conversion stage of the process are supplied to a vaporizing chamber, preferably operated at substantially reduced pressure relative to that employed in the topping and fractionating stage of the process, wherefrom a non-vaporous residue comprising good quality fuel oil is recovered. The vaporous products from the vaporizing chamher are subjected to fractionation for the recoveryof their low-boiling fractions, comprising good quality motor fuel, and higher boiling fractions, which latter are condensed as reflux condensate, the reflux condensate is subjected to further conversion under independently controlled conditions for the production of additional yields of good quality motor fuel and fuel oil residue and the resulting products are supplied to said reduced pressure vaporizing chamber.

Various modifications of the specific embodiment of the invention above described may be employed without departing from its spirit and scope, some of which modifications will be described in connection with the following description of the accompanying diagrammatic drawing.

The drawing illustrates one specific form of apparatus embodying the features of the present invention and in which the operation of the process of the invention may be successfully accomplished. It will be understood, however, that 1 the invention is not limited to use in the specific form of apparatus here illustrated.

Raw oil charging stock for the process, preferably of the character above mentioned, is supplied through line I and valve 2 to pump 3 by 15 means of which it is fed through line 4., valve 5, line 6 and valve 8 into column 9. The charging stock is commingled in line 6 with hot conversion products from heating coil I0, whereby it is heated to a temperature sufficient to effect its substantial vaporization and fractionation in column 9. It will be understood that the charging stock may, if desired, be preheated to any desired temperature in any well known manner, not illustrated in the drawing, prior to its introduction into line 6, for example, by indirect contact with hot vapors or liquids from within the system by means of fiue gases from either or both cracking furnaces of the process or by means of heat derived from any desired external 30 source.

Column El is preferably operated at a substantial superatmospheric pressure, although sub stantially atmospheric or even sub-atmospheric pressure may be employed in this zone, if desired. Components of the vaporous materials supplied to this zone, boiling within the range of motor fuel and of good antiknock value, including any straight-run gasoline or gasoline fractions of the crude meeting the antiknock 40 requirements, as well as good quality motor fuel conversion products from heating coil ID, are withdrawn from the upper portion of column 9 through line l2 and may pass through valve l3 to cooling and condensation in condenser 14, 45 from which the resulting distillate and gas passes through line l5 and valve IE to collection and separation in receiver ll. Uncondensable gas may be released from the receiver through line l8 and valve I9, distillate may be withdrawn from receiver 11 through line 20 and valve 2| to storage or to any desired further treatment. If desired, instead of being subjected to separate condensation and collection the vaporous products from line l2 may be directed through line 22 and valve 23 into fractionator 50 or through line 24 and valve 25 into line 5|, to commingle with the vaporous products from fractionator 59, in either of which latter cases the motor fuel product from column 9 is blended with the motor fuel product from the second conversion stage of the process and subjected to condensation and collected therewith in receiver 5% as will be hereinafter more fully described.

If desired, a regulated portion of the distillate collected in receiver ll may be recirculated by well known means, not shown in the drawing, to the upper portion of column 9 to cool and assist fractionation of the vaporous products. in the upper portion of this zone, thereby serving to regulate the vapor outlet temperature from column 9 and controlling the end-boiling point of the distillate collected in receiver H. Preferably, in case the distillate product from column 9 is commingled with the motorfuel products from the second conversion stage of the process and collected in receiver 59, a regulated portion of the vapors from line I2 are continuously condensed and returned as refluxing material to the upper portion of column 9, rather than returning the full boiling range distillate from receiver 56 as refluxing material to this zone. This is not considered, in itself, a novel or essential feature of the present invention and therefore the well known means whereby it may be accomplished are not illustrated in the drawing.

Intermediate components of the vaporous materials supplied to column 9, including any straight-run gasoline fractions of the crude of poor antiknock value and similar motor fuel conversion products from heating coil in as well as, if desired, somewhat higher boiling materials such as straight-run kerosene or kerosene distillate, light gas oil and conversion products of similar boiling range from heating coil I0, are withdrawn from any suitable intermediate point or points in column 9, for example, through line 26 and valve 2'! to pump 28 by means of which they are supplied through line 29, valve 39 and line 3 2 to conversion in heating coil IN.

A furnace ll of any suitable form supplies the required heat to the oil passing through heating coil I!) to bring it to the desired conversion temperature, preferably at a substantial superatmospheric pressure and the heated conversion prod nets are discharged therefrom through line 6 and pass through valves 1 and 8 into column 9, being cooled sufliciently in line 9, by direct contact with charging stock supplied thereto, as previously described, to prevent their excessive further conversion in column 9.

It is also within the scope of the present invention, if desired, to supply a secondary charging stock, preferably comprising a relatively light distillate, from any desired external source, to conversion in heating coil i9, by means of line 3!, valve 32, pump 33, line 36 and valve 35. This is particularly desirable in case the quantity of desired intermediate products obtainable from column 9 for conversion in heating coil it is not sufficient to heat the crude charging stock suppiled to line 6 to the desired temperature. Secondary charging stock may be supplied, as described, to heating coil ii] when the operation of the process is first started in order to supply the required heat to the crude by commingling the highly heated secondary charging stock and crude oil in line 6, prior to their introduction into column 9, and the quantity of secondary charging stock supplied to heating coil Iii may be diminished or entirely stopped as the operation progresses to a point where the desired quantity of intermediate fractions is available from column 9 for conversion in heating coil l9.

As an example of another suitable method of starting the operation of the process, the crude charging stock may be supplied in heated state to column 9, for example, by passing the same through heating coil in or by any other well known heating means, not illustrated, intermediate fractions of the charging stock being meanwhile recovered from column 9 until a sufficient quantity is obtained to supply the required conversion stock to heating coil Ill and divert the raw oil feed to line 6.

Ordinarily the low-boiling character of the oil supplied for conversion to heating coil l0 and the conversion conditions maintained in this zone are such that the resulting products are primarily low-boiling motor fuel fractions of high antiknock value, relatively heavy polymerization products or residual liquid and gas. This being the case, no large quantities of intermediate conversion products are returned from column 9 to further conversion in heating coil It] and the oil supplied from column 9 to this zone comprises, primarily, straight-run intermediate fractions of the charging stock.

High-boiling components of the charging stock and of the conversion products from heating coil l9 supplied to column 9, boiling above the range of the desired intermediate fractions from this zone which are supplied to heating coil l0, collect within the lower portion of the column and are withdrawn therefrom through line 36, from which they may be supplied through line 3'! and valve 38 to vaporizing chamber 43. Ordinarily, when a substantial superatmospheric pressure is employed in column 9, a sufficiently reduced pressure is employed in chamber 43 to obviate the use of a pump for transferring the oil from column 9 to chamber 43/ When such is not the case the oil from the lower portion of column 9 may pass through valve 39, in line 36, to a suitable pump 49 by means of which it is fed through line H, valve 42 and line 31 to chamber 43.

Further vaporization of the oil supplied from column 9 to chamber 43 is accomplished in the latter zone by means of a substantial reduction in pressure in this zone or by the additional heating of the oil or both. When desired, a regulated portion of the hot conversion products from heating coil it may be diverted from line 6 through line 64 and valve 45 into'line 31 to comrningle with the oil supplied from column 9 to chamber 43, in order to heat the same and assist its further vaporization. Also further vaporization of the oil supplied from column 9 to chamber 43 will ordinarily be assisted by the introduction of other hot conversion products into chamber t3, as will be later more fully described.

Residual liquid remaining unvaporized in chamber t3, preferably comprising good quality fuel oil, containing heavy components of the oil supplied to this zone from column 9 as well as residual liquid conversion products from the second cracking stage of the process, which will be later more fully described, is withdrawn from the lower portion of chamber 43 through line 46 and valve 3? to cooling and storage or to any desired further treatment.

vaporous products pass from chamber 43 through line 48 and valve 49 to fractionation in fractionator 58, wherein their components boiling above the range of the desired final light distillate product of this portion of the system, are condensed as reflux condensate.

Fractionated vapors of the desired end-boiling point, preferably comprising motor fuel of high antiknock value, are withdrawn, together with uncondensable gas, from the upper portion of fractionator 50 through line 5| and valve 52 to condenser 53, wherein they are subjected to cooling and condensation. The resulting distillate and gas passes through line 54 and valve 55 to collection and separation in receiver 56. Uncondensable gas may be released from the receiver through line 51 and valve 58. Distillate may be withdrawn from receiver 56 through line 59 and valve 60 tostorage or to any desired further treatment. When desired, a regulated portion of the distillate collected in receiver 56 may be recirculated by well known means, not shown in the drawing, to the upper portion of fractionator 50 to assist cooling and fractionation of the vapors in this zone and to maintain the desired vapor outlet temperature from the fractionator.

Reflux condensate formed in fractionator 50 is withdrawn from the lower portion thereof through line GI and valve 62 to pump 63 by means of which it is supplied through line 64 and valve 65 to conversion in heating coil 66.

The oil supplied to heating coil 66 is brought to the desired conversion temperature, preferably at a substantial superatmospheric pressure, by means of heat supplied by a furnace 61, of any suitable form, and the heated materials are supplied through line 68 and valve 69 to reaction chamber H3.

Chamber [0 is also preferably maintained at a substantial superatmosphericv pressure and, although not illustrated in the drawing, is preferably well insulated in order to prevent the excessive loss of heat by radiation, so that conversion of the heated products supplied to this zone from heating coil 66, and more particularly their vaporous components, may continue in the reaction chamber. In the case here illustrated both vaporous and liquid conversion products are withdrawn from the lower portion of reaction chamber 10 and pass in commingled state through line H and valve 12 to vaporizing chamber 43, which is preferably maintained at a substantially reduced pressure relative to that employed in chamber 10 and wherein further vaporization of the liquid conversion products from chamber 10, as well as further vaporization of the liquid supplied to chamber 43 from column 9, as previously described, is accomplished.

The conversion conditions employed at the outlet from the first mentioned heating coil of the process, to which intermediate fractions from the topping and fractionating column are supplied, may range, for example, from. 950 to 1050 F., or thereabouts, with a superatmospheric pressure at V this point in the system preferably of the order of 300 to 1000 pounds, or thereabouts, per square inch. Preferably a substantial superatmospheric pressure of the order of to 500 pounds, or thereabouts, per square inch is employed in the topping and iractionating column although, when desired, lower pressures down to substantially atmospheric or even subatmospheric pressure may be employed in this zone. The heating coil of the second conversion stage of the process may utilize an outlet temperature ranging, for example, from. 900 to 1000 F., or thereabouts, preferably with a substantial superatmospheric pressure, measured at the outlet from the heating coil, of from 100 to 500 pounds, or thereabouts,

per square inch. Substantially the same pressure is preferably employed in the reaction chamber. although a somewhat reduced superatmospheric pressure may be employed in this zone, if desired. A substantially reduced pressure relative to that employed in the reaction chamber is preferred in the vaporizing chamber and may range, for example, from substantially atmospheric to 100 pounds, or thereabouts, per square inch. The succeeding fractionating, condensing and collecting portions of the system may utilize pressures substantially equalized with or somewhat reduced relative to the pressure employed in the vaporizing chamber As a specific example of the operation of the process of the present invention, in an apparatus such as illustrated and above described, the charging stock is a Mid-Continent crude of about 36 A. P. I. gravity, containing about 25 percent of straight-run gasoline boiling up to 437 F.'

This material is commingled with the heated products passing from the first cracking coil of the process to the vaporizing and fractionating column whereby it is heated sufliciently to effect its substantial vaporization, and a motor fuel of about 350 F. end-boiling point is recovered as the overhead product from the topping and fractionating column. The fractions of crude boiling between approximately 350 and 550 F., together with any intermediate conversion products of the first conversion stage of the process of similar boiling range, are withdrawn as a side stream from the topping and fractionating column and subjected in the heating coil to an outlet conversion temperature of approximately if 980 F. at a superatmospheric pressure of about 1000 pounds per square inch. The products are cooled by being commingled with the crude charging stock, prior to their introduction into the topping and fractionating column and a superatmospheric pressure of about 200 pounds per square inch is employed in this zone. Bottoms from the topping and fractionating column are supplied to a vaporizing chamber operated at a reduced superatmospheric pressure of about 50 pounds per square inch wherefrom residual liquid, comprising good quality fuel oil, is recovered and the vaporous products from this zone are subjected to fractionation. Reflux condensate from the fractionator is subjected in a separate heating coil to a conversion temperature of approximately 950 F. at a superatmospheric pressure of about 400 pounds per square inch. The heated products are passed through a reaction chamber, operated at substantially the same pressure, into the reduction pressure vaporizing chamber. A motor fuel product of about 400 F. end-boiling point is recovered as the light distillate product from the fractionator of the second cracking stage of the process and is blended with lower end-point motor fuel recovered from the topping and fractionating column as the final motor fuel product of the process.

An operation such as above described may yield, per barrel of charging stock, about 58 percent of motor fuel having an antiknock value equivalent to an octane number of approximately 72 and about 30 percent of good quality fuel oil, the remaining 12 percent, or thereabouts, being chargeable principally to uncondensable gas and loss.

I claim as my invention:

1. A process for the conversion of hydrocarbon oils which comprises subjecting charging stock for the process to fractional distillation by commingling the same with hot conversion products from a heating coil whereby the conimingled conversion products and chargin stock are sep arated into fractionated vapors, comprising desirable low-boiling fractions which are condensed and collected, intermediate fractions and highboiling fractions supplying the intermediate fractions to the heating coil for conversion, subjecting the high-boiling fractions to further vaporization, subjecting the resulting vapors to fractionation, subjecting reflux condensate resulting from said fractionation to conversion temperature at superatmospheric pressure in a separate heating coil and communicating reaction chamber, subjecting the resulting liquid conversion products to further vaporization at substantially reduced pressure, together with the aforementioned highboiling fractions, subjecting the vaporous conversion products to said fractionation, together with the vapors resulting from said further vaporization of the liquid conversion products and high-boiling fractions, subjecting fractionated vapors of the desired end-boil ng point to condensation and collecting the resulting products, the process being further characterized in that said further vaporization of the high-boiling fractions and liquid conversion products is assisted by comrningling therewith a regulated portion of the hot conversion products from the first mentioned heating coil.

2. A conversion process which comprises cracking reflux condensate under pressure in a cracking zone and then introducing the same to a vapor separating zone maintained under lower pressure than the cracking zone, simultaneously cracking a second reflux condensate in a second cracking zone, introducing a portion of the cracked second condensate to said separating zone, commingling another portion of the cracked second condensate with charging oil for the process, separating the resultant mixture into vapors and unvaporized oil, fractionating the vapors to condense heavier fractions thereof and supplying such condensed fractions to the second cracking zone as said second reflux condensate, introducing said unvaporized oil to said separating zone to commingle with the other hydrocarbons introduced thereto, separating the commingled hydrocarbons in the separating zone into vapors and residue, fractionating these vapors and supplying resultant condensed portions thereof to the first-mentioned cracking zone as the first-named reflux condensate, and finally condensing the fractionated vapors.

KENNETH SWARTWOOD. 

